Just in case anyone is wondering, YYZ T3 pre-clearance has one GE kiosk, nestled between the two Nexus ones. The rent-a-cop moat dragons do check the customs declaration cards before going in to the CBP area. Not sure if telling him I'm a Nexus member would help or not.

It took me about 2 minutes to get through customs. My coworker took about 45 minutes. Totally worth it, IMO.